In the television broadcast industry, there are several types of television production methodologies, including electronic news gathering/satellite news gathering (ENG/SNG), electronic field production (EFP) and outside broadcast (OB). ENG/SNG applications typically feature a single camera with a built-in video tape recorder (VTR) which is most often used as a stand-alone camcorder for recording live events locally to tape. FIG. 1 shows a prior art camera system 12. This camera can also serve as a “live” camera from the scene of the news event. At that point, it is commonly connected to a video production vehicle control center 11 via either copper cables or coaxial cables 17.
In the copper cable approach, the camera is connected to the truck with multiple copper cables which typically include one-to-three coax cables with BNC connectors for video signals and one-to-four shielded twisted audio pairs with XLR connectors for audio and intercom signals as well as power if the camera is not powered by a local battery. Alternatively, a minority of crews make use of products which multiplex all of the required signals, as well as power, over a single coax cable. U.S. Pat. No. 5,345,592 discloses such a system.
In Electronic Field Production (EFP), multiple cameras connect to a “production center” (usually a small truck) via copper cables or coax, or via another cable, known as “multicore.” Multicore is a 26-conductor cable that carries power and all of the required signals over discreet copper wires. Multicore is limited in distance, and is heavy, inflexible, expensive, and hard to repair in the field.
Outside Broadcast (OB) features multiple cameras (three or more) serviced by cameras with triaxial capability. This application includes sports, live music concerts, scripted programs shot outside of studios, and other shows where large crews shoot action that is confined within a prescribed area and is fairly predictable. The OB camera can be remotely controlled and powered from a local or distant camera control unit (CCU), sometimes called a base station, through a transmission medium known as triaxial cable.
The triaxial cable is a shielded coaxial cable designed to simultaneously transmit various bi-directional information and/or control signals and provide power from the CCU to the camera. Signals typically may include program video (component, composite, serial digital interface, high definition or other), program audio, return video, viewfinder video, genlock, return audio, IFB (interrupt foldback), Teleprompter, tally, call, intercom, and bi-directional camera control data. These signals may be analog, such as AM or FM, and/or digital in nature. Power may be in the form of AC or DC. Since there is typically only one physical cable, it is the function of the camera system's triaxial adapter to encode and/or modulate the required video, audio, intercommunications and data signals onto the proper frequencies. These frequencies are typically frequency division multiplexed for transmission, with assigned frequencies traveling in their specified directions on the triaxial cable. Other techniques, such as digital hybrid transmission, may also be used in addition to frequency division multiplexing techniques. The triaxial adapter demodulates the composite signal at either of the receiving ends of the triaxial cable into the respective baseband signals. The triaxial adapter may be contained within the camera and/or CCU ends, or may be separate units that attach to the camera and/or CCU ends.
Since the information signals are typically high frequency broadband RF signals, the effective distance over which the camera and CCU can communicate and operate is limited to one to three kilometers. In addition, a trend in the industry has been towards cameras having higher performance and wider information bandwidths, thus further limiting the distance of a wideband, component triaxial camera system to approximately one kilometer. In order to compensate, users may utilize a larger, heavier cable, which may increase distance, but also increases time and labor to deploy and take up the cable. This distance limitation often interferes with the user's ability to produce the desired programming.
Some camera manufacturers provide a fiber optic interface directly on the camera and on the CCU. However, these solutions can require significant investments in new cameras, CCUs and supporting infrastructure.
Video cameras for ENG or EFP applications typically are equipped with a specialized battery mount that provides a rugged, secure and reliable attachment of the battery to the camera. Known systems for battery mounting include Anton/Bauer, PAG, and Sony V-mount.